Hammer-mill hammer



J. A. TANKEIRSLEY April 8, 1941.

HAMMER-MILL HAMMER Filed Aug. 2, 1939- IN VENTOR.

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Patent ed Apr. 8, 1941 HAMTMER-IVIILL HAMMER James A. Tankersley, Indianapolis, Ind, assignor to Heat Treating Incorporated, Indianapolis, Ind., a corporation of Indiana Application August 2, 1939, Serial No. 238,037

6 Claims.

My invention relates to hammer mills and more particularly to the hammers employed therein. It is the object of my invention to produce a hammer which will possess a more eflicient cutting action and have a longer effective life than prior hammers of which I am aware.

their cutting teeth, are desirably hardened; but

I find that the effective life may be even further increased if one of the side faces of each tooth is left soft. As the cutting edge of a tooth mer, one (ll) defined by the side of the hammer, one (l8) defined by a face of the hammer, and the fourth (i9) defined by a side wall of the groove M. In the preferred form of my invention at least one of the latter two faces, desirably the face I9, is made relatively soft so that as it wears away the tooth I will become thinner.

The differential hardness of the faces in the cutting tooth i5 may be obtained in various ways. For example, I may case-carburize the hammers l3 before the grooves it are provided therein, and then cut the grooves l4 exposing the so constituted wears away, the relatively soft side face also wears away, thus keeping the tooth thin and sharp.

The accompanying drawing illustrates my invention: Fig. 1 is a fragmental transverse section through a hammer mill; Fig. 2 is an end elevation of one of the hammers; Fig. 3 is a section on the line 3-3 of Fig, 2; Fig. 4 is an iso-- metric view on an enlarged scale, illustrating one corner of a hammer embodying my invention; and Fig. 5 is a fragmental section on the line 55 of Fig. 3. I v

The hammer mill shown in Fig. 1 includes a foraminous screen l0 and a rotor ll rotatably mounted within such screen. The rotor includes .an annular series of axially extending rods l2 upon which the hammers l3 are pivotally mounted.

Each hammer I3 is shown as consisting of a flat plate of metal having in each of its .outer corners a generally V-shaped groove II which extends inwardly along the side face of the hammer from the outer end face thereof. Each of these grooves divides the outer corner of the hammer to form two teeth l5. If desired-and I have so indicated in the drawing-each of the hammers 13 may be reversible on the rotor H, being provided with symmetrically, arranged holes I! either of which may receive the rod l2. If this is done, all four corners of each hammer i3 are grooved as indicated in Figs. 2, 3, and 4; V

Each of the teeth l5 has four faces (seeFig. 4) one (It) defined by the end face of the hamone side of each tooth, the sharpness of the teeth pling. As the tooth-face ll wears away under uncarburized core of the hammer. In the preferred method, the hammers are not quenched at the conclusion of the carburizing process but instead are left soft, the grooves it cut as by milling, and the hammer then hardened. If the hammers are quenched at the conclusion of the carburizing process, thereby hardening them, the grooves l4 may be cut by grinding.

Alternatively, the grooves it may be provided before the hammer is carburized, and the side tooth-faces which are to remain soft protected against carburization, as by copper-plating. In general, I contemplate the use of any hardening process which will render one side face of each cutting tooth relatively soft.

In the absence of the grooves l4, each corner of the hammer would form, in effect, a single cutting tooth. By providing a groove M in each corner of the hammer, each corner of the hammer is made to possess two'cutting teeth; and the cutting action is consequently rendered more effective.

Moreover, because of the relative softness of is preserved in spite of wear. This will be apparent from Fig. 5, which is an enlarged crosssection through one of the teeth I5, the hardened portion of the tooth being indicated by stipthe influence of the cutting action, the relatively soft side face l9 also wears away, the shape of the tooth after considerable wear being indicated by the dotted lines. It will be evident that in spite of wear the tooth-face ll will not increase in width and that as a result the tooth will remain sharp for extended periods of use.

I claim as my invention:

1.-A hammer for use in hammer mills,'comprising a generally rectangular metal plate adaptrrer-mill rotor, said plate being provided at at least one of its outer comerswith a groove opening in the end face of the hammer and extending inwardly along the adjacent side face of the hammer, the walls of such groove being softer than the outersurfaces of the hammer adjacent such outer corner.

2. A hammer for use in hammer mills, comprising a generally rectangular metal plate adapted at one end for pivotal attachment to the hammer-mill rotor, said plate being provided at at 1 least one of its outer corners with a groove opening in the end face of the hammer and extending inwardly along the adjacent side face of the hammer, to form two cutting teeth, at least i one side face of each of said teeth beingsofter than the other faces thereof.

3. A hammer for use in hammer-mills, said hammer being adapted at one end for pivotal attachment to the hammer-mill rotor and provided at the other end with a cutting tooth having opposite side faces disposed generally perpendicular to the axis of pivotal attachment of the hammer to the rotor, at least one of the side faces of said tooth being softer than the remaining faces thereof.

4. The invention set forth in claim 1 with the addition that said hammer is of low-carbon steel. the outer faces of the hammer being carburized and the walls of said groove being uncarburized. 5. The invention set forth in claim 3 withv the addition that said hammer and tooth are of low-carbon steel, the harder faces of said tooth being carburized and the softer face or faces uncarburized.

6. A hammer for use in hammer-mills, said hammer being adapted at one end for pivotal attachment to the hammer-mill rotor and provided at the other end with an integral cutting tooth having a relatively hard portion and a relatively soft portion, the hard portion being of approximately uniform thickness and extending generally perpendicularly to the axis of the hammer-mill rotor and the softer portion being contiguous to said harder portiomextending generally perpendicular to the axis of the hammermill rotor, and being of increasing thickness toward the base of the tooth.

JAMES A. TANUIRSLEY. 

